Thermoplastic elastomer composition

ABSTRACT

The present invention provides a thermoplastic elastomer composition which is not only satisfactory in rubber-like characteristics and moldability but also satisfactory in both permanent compression set and vibration damping properties and comprises an unsaturated bond-containing isobutylene polymer (A) and an olefinic resin (B).

RELATED APPLICATIONS

This application is a nationalization of PCT Application No.PCT/JP02/06538 filed on Jun. 28, 2002. This application claims priorityfrom Japanese Application No. 2001-197425 filed on Jun. 28, 2001:Japanese Application No. 2001-197426 filed on Jun. 28, 2001; andJapanese Application No. 2001-209022 filed on Jul. 10, 2001.

TECHNICAL FIELD

The present invention relates to a thermoplastic elastomer composition.

BACKGROUND TECHNOLOGY

Heretofore, as high polymer materials having rubber-like elasticity,those obtained by formulating a crosslinking agent, a reinforcing agent,and the like in various rubbers, such as natural and synthetic rubbers,and crosslinking the resulting compositions at high temperature and highpressure have been used broadly. However, such rubbers require prolongedcrosslinking and molding under high-temperature, high-pressureconditions, thus being poor in processability. Moreover, the crosslinkedrubbers do not exhibit thermoplasticity so that, unlike thermoplasticresins, recycle molding is generally infeasible. For this reason, recentyears have seen the development of several recyclable thermoplasticelastomers which may be easily reprocessed into shaped articles byutilizing the universal melt-molding techniques such as hot-pressmolding, injection molding and extrusion molding as it is the case withordinary thermoplastic resins. As such thermoplastic elastomers, severalpolymers in the olefin, urethane, ester, styrenic, and vinyl chlorideseries have been developed and are on the market today.

Among these polymers, styrenic thermoplastic elastomers are highlyflexible and exhibit satisfactory rubber-like elasticity at atmospherictemperature. As such styrenic thermoplastic elastomers,styrene-butadiene-styrene block copolymer (SBS),styrene-isoprene-styrene block copolymer (SIS), and the correspondinghydrogenated elastomers such as styrene-ethylenebutylene-styrene blockcopolymer (SEBS) and styrene-ethylenepropylene-styrene block copolymer(SEPS) are known. However, these block copolymers are inadequate inpermanent compression set.

Meanwhile, as a thermoplastic elastomer having good flexibility,exhibiting good rubber-like elasticity at atmospheric temperature, andhaving satisfactory vibration damping properties, an isobutylene blockcopolymer comprising a polymer block composed predominantly ofisobutylene and a polymer block composed predominantly of an aromaticvinyl compound is known (U.S. Pat. No. 4,276,394). However, thisisobutylene block copolymer has also proved unsatisfactory in the degreeof compressive deformation on heating (permanent compression set) and inrubber-like elasticity at high temperature.

Also known is a thermoplastic polymer composition comprising acrosslinking product of an isobutylene block copolymer componentcontaining a polymer block composed predominantly of isobutylene and arubber component (WO98/14518). This composition is outstanding in gasbarrier and sealing properties but has been found to have the drawbackthat it is still unsatisfactory in permanent compression set, giving avalue of 35 to 65 under the condition of 70° C.×22 hours.

Thus, there has not been known a thermoplastic elastomer satisfactory inall of moldability, permanent compression set, and vibration dampingproperties.

SUMMARY OF THE INVENTION

Developed in the above state of the art, the present invention has forits object to provide a thermoplastic elastomer composition which is notonly satisfactory in rubber-like characteristics and moldability butalso satisfactory in both permanent compression set and vibrationdamping properties.

The inventors of the present invention researched in earnest foraccomplishing the above object and have found that a thermoplasticelastomer composition comprising an unsaturated bond-containingisobutylene polymer and an olefinic resin is capable of expressing allthe above-mentioned characteristics. The present invention has beendeveloped on the basis of the above finding.

The present invention, therefore, is directed to a thermoplasticelastomer composition comprising an unsaturated bond-containingisobutylene polymer (A) and an olefinic resin (B).

The unsaturated bond-containing isobutylene polymer (A) mentioned aboveis preferably a block copolymer comprising a polymer block (a) composedpredominantly of isobutylene and a polymer block (b) composedpredominantly of an aromatic vinyl compound. Moreover, in the case wherethe unsaturated bond-containing isobutylene polymer (A) is the blockcopolymer mentioned just above, the unsaturated bond-containingisobutylene polymer (A) preferably contains said unsaturated bond withinthe molecular chain of the polymer block (b) composed predominantly ofan aromatic vinyl compound.

Furthermore, the unsaturated bond-containing isobutylene polymer (A) ispreferably an alkenyl group-terminated polymer.

It is also preferable that the olefinic resin (B) content should be 10to 200 weight parts relative to 100 weight parts of the unsaturatedbond-containing isobutylene polymer (A).

The unsaturated bond-containing isobutylene polymer (A) is preferably apolymer produced by synthesizing an isobutylene polymer not containingan unsaturated bond in the first place and then introducing anunsaturated bond thereinto.

Furthermore, the unsaturated bond-containing isobutylene polymer (A) ispreferably an allyl-terminated polymer produced by causingallyltrimethylsilane to act on a polymer not containing an unsaturatedbond at the molecular chain terminus but terminating in a chlorine atom.

In the thermoplastic elastomer composition of the invention, theunsaturated bond-containing isobutylene polymer (A) preferably has anintermolecularly crosslinked structure.

The crosslinking of the unsaturated bond-containing isobutylene polymer(A) may be effected at any of the following stages, i.e. the stage ofmelt-kneading of the unsaturated bond-containing isobutylene polymer (A)with the olefinic resin (B), a stage preceding the melt-kneading of theunsaturated bond-containing isobutylene polymer (A) with the olefinicresin (B), or a stage following the melt-kneading of the unsaturatedbond-containing isobutylene polymer (A) with the olefinic resin (B).Preferably, the crosslinking is effected with a crosslinking agent.

Preferably, the thermoplastic elastomer composition of the presentinvention comprises a plasticizer (C). The plasticizer (C) is preferablya paraffinic oil.

The unsaturated bond-containing isobutylene polymer (A) is preferably apolymer having a number average molecular weight of 1,000 to 500,000 andcontaining an average of at least 0.2 unsaturated bond per molecule atthe molecular chain terminus.

The unsaturated bond-containing isobutylene polymer (A) contains amonomer unit derived from isobutylene in a proportion of not less than50 weight % based on the total weight of the polymer (A).

Further, the preferred olefinic resin (B) is polyethylene orpolypropylene.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is now described in detail.

The thermoplastic elastomer composition of the invention comprises anunsaturated bond-containing isobutylene polymer (A) and an olefinicresin (B).

Unsaturated Bond-Containing Isobutylene Polymer (A)

The unsaturated bond-containing isobutylene polymer (A) for use in thepresent invention is not particularly restricted provided that itcontains a monomer unit derived from isobutylene and an unsaturatedbond.

The structure of said isobutylene polymer may be a homopolymer ofisobutylene, a random copolymer of isobutylene, or a block copolymer ofisobutylene.

In the case where the isobutylene polymer is a homopolymer ofisobutylene or a random copolymer of isobutylene, the monomer unitderived from isobutylene is preferably in a proportion not less than 50weight %, more preferably not less than 70 weight %, still morepreferably not less than 90 weight %, based on the total weight of thepolymer (A).

In the case where the isobutylene polymer is a block copolymer ofisobutylene, it suffices that the copolymer contains a polymer blockcomposed predominantly of isobutylene and otherwise there is norestriction. Regarding this polymer block composed predominantly ofisobutylene, the monomer unit derived from isobutylene is preferably ina proportion not less than 50 weight %, more preferably not less than 70weight %, still more preferably not less than 90 weight %, based on thetotal weight of the particular polymer block.

In this connection, the monomer or monomers other than isobutylene inthe isobutylene polymer are not particularly restricted provided thatthey are cationically polymerizable monomer components. Thus, suchmonomers as aromatic vinyl compounds, aliphatic olefins other thanisobutylene, dienes such as isoprene, butadiene, divinylbenzene, etc.,vinyl ethers, and β-pinene, among others, can be mentioned. These may beused each independently or in a combination of two or more species.

The particularly preferred block copolymer of isobutylene is onecomprising a polymer block (a) composed predominantly of isobutylene anda polymer block (b) composed predominantly of an aromatic vinylcompound. Regarding the polymer block (b) composed predominantly of anaromatic vinyl compound, the monomer unit derived from the aromaticvinyl compound is preferably in a proportion not less than 50 weight %,more preferably not less than 70 weight %, still more preferably notless than 90 weight %, based on the total weight of the particularpolymer block.

The aromatic vinyl compound is not particularly restricted but includesstyrene, α-methylstyrene, β-methylstyrene, p-methylstyrene,t-butylstyrene, monochlorostyrene, dichlorostyrene, methoxystyrene andindene, among others. These may be used each independently or in acombination of two or more species. Among the compounds mentioned above,styrene, α-methylstyrene, p-methylstyrene and indene are preferred interms of the balance among cost, physical properties, and productivity.Moreover, two or more species may be chosen from among them and used, ifdesired.

The monomer or monomers other than the aromatic vinyl compound in saidpolymer block (b) composed predominantly of an aromatic vinyl compoundare not particularly restricted provided that they are cationicallypolymerizable monomers but, for example, such monomers as aliphaticolefins, dienes, vinyl ethers, and β-pinene can be mentioned.

The relative amount of the polymer block (a) composed predominantly ofisobutylene and that of the polymer block (b) composed predominantly ofan aromatic vinyl compound in the isobutylene block copolymer are notparticularly restricted but, in consideration of the balance betweenprocessability and physical properties, it is preferable to insure thatthe polymer block (a) composed predominantly of isobutylene accounts for95 to 20 weight % and the polymer block (b) composed predominantly of anaromatic vinyl compound account for 5 to 80 weight %. The particularlypreferred proportions are that the polymer block (a) composedpredominantly of isobutylene accounts for 90 to 60 weight % and thepolymer block (b) composed predominantly of an aromatic vinyl compoundaccounts for 10 to 40 weight %.

The structure of the isobutylene block copolymer which is preferred interms of the physical properties and processability of the finalcomposition comprises at least one polymer block (a) composedpredominantly of isobutylene and at least two polymer blocks (b)composed predominantly of an aromatic vinyl compound.

The copolymer structure mentioned above is not particularly restrictedbut includes a triblock structure consisting of (b)-(a)-(b) blocks, amulti-block structure consisting of repeats of the [(b)-(a)] block, anda stellate structure with arms each consisting in a diblock copolymer of(b)-(a) blocks, among others. These may be used each independently or ina combination of two or more species.

Furthermore, such an isobutylene block copolymer may contain at leastone of a homopolymer of isobutylene, a random copolymer consistingpredominantly of the monomer unit derived from isobutylene, ahomopolymer of the aromatic vinyl compound, a random copolymerconsisting predominantly of the monomer unit derived from the aromaticvinyl compound, and a diblock copolymer of the (a)-(b) structure. Fromthe standpoint of physical properties and processability, however, thepreferred structure contains at least 50 weight % of an isobutyleneblock copolymer comprising at least one polymer block (a) composedpredominantly of isobutylene and at least two polymer blocks (b)composed predominantly of an aromatic vinyl compound.

Isobutylene polymers can be produced by cationic polymerization ofisobutylene alone or isobutylene and one or more other monomers.

The unsaturated bond in the isobutylene block copolymer is notparticularly restricted provided that it is a carbon-carbon unsaturatedbond. Particularly preferred is a carbon-carbon double bond. In the casewhere the unsaturated bond-containing isobutylene polymer (A) has anintermolecularly crosslinked structure, said unsaturated bond ispreferably a bond which is reactive to the crosslinking agent describedhereinafter, for example a hydrosilyl group-containing compound or aperoxy compound, or reactive to heat.

The unsaturated bond-containing group in the isobutylene block copolymerincludes alkenyl, acryloyl and methacryloyl, among others. The alkenylmentioned just above includes aliphatic unsaturated hydrocarbon groups,such as vinyl, allyl, methylvinyl, propenyl, butenyl, pentenyl, hexenyl,etc. and cyclic unsaturated hydrocarbon groups, such as cyclopropenyl,cyclobutenyl, cyclopentenyl, cyclohexenyl, and so forth.

Among these, in the case where the crosslinking is effected with ahydrosilyl group-containing compound, allyl group is preferred.

When said crosslinking is effected with a hydrosilyl group-containingcompound, hydrosilyl group-containing linear polysiloxane is preferred.When the crosslinking is effected with an organic peroxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexane is preferred in terms of odor,coloring potential, and scorch stability. Moreover, when heat is usedfor crosslinking, the temperature condition of not less than 100° C. ispreferred.

In the isobutylene polymer (A), the unsaturated bond may be located atthe molecular chain terminus of the polymer or in a group pendant fromthe molecular chain of the polymer, or even be located at both sites.Furthermore, in the case where the isobutylene polymer (A) is a blockcopolymer comprising a polymer block (a) composed predominantly ofisobutylene and a polymer block (b) composed predominantly of anaromatic vinyl compound, the unsaturated bond may be located at themolecular chain terminus of the polymer or, optionally, a groupcontaining the unsaturated bond may be located within the aromatic ringof the monomer unit derived from the aromatic vinyl compound.

The number of unsaturated bonds in the isobutylene polymer (A) ispreferably not less than 0.1 per polymer molecule on the average, morepreferably not less than 0.2, still more preferably not less than 0.5,especially not less than 1, for a more satisfactory permanentcompression set can then be attained. If the number of unsaturated bondsis too large, moldability tends to be sacrificed. Therefore, the averagenumber of unsaturated bonds per polymer molecule preferably not morethan 10, more preferably not more than 5.

The unsaturated bond-containing isobutylene polymer (A) can be producedby the cationic copolymerization of a monomer component comprisingisobutylene and a monomer containing said unsaturated bond or,alternatively, by modifying an isobutylene polymer not containing anunsaturated bond with an unsaturated bond-containing compound.

More particularly, there may be used a technology which, as disclosed inJapanese Kokai Publication Hei-3-152164 and Japanese Kokai PublicationHei-7-304909, comprises reacting a polymer having a hydroxyl or the likefunctional group with an unsaturated bond-containing compound to therebyintroduce the unsaturated bond into the polymer. Moreover, forintroducing an unsaturated bond into a halogen-containing polymer, therecan be used a method which comprises carrying out a Friedel-Craftsreaction with an alkenyl phenyl ether, a method comprising asubstitution reaction with allyltrimethylsilane or the like in thepresence of a Lewis acid, or a method which comprises carrying out aFriedel-Crafts reaction with a phenol compound to introduce a hydroxylgroup and, then, carrying out the alkenyl group-introducing reactionreferred to above. Furthermore, as disclosed in U.S. Pat. No. 4,316,973,Japanese Kokai Publication Sho-63-105005, and Japanese Kokai PublicationHei-4-288309, the unsaturated bond may be introduced at polymerizationof the monomer.

The isobutylene block copolymer containing an unsaturated bond in apendant group from the molecular chain can also be obtained by modifyingthe isobutylene block copolymer not containing an unsaturated bond withan unsaturated bond-containing acid chloride and/or acid anhydride.

The above modification, in the case where the isobutylene polymer is ablock copolymer comprising a polymer block (a) composed predominantly ofisobutylene and a polymer block (b) composed predominantly of anaromatic vinyl compound, can be effected by causing an unsaturatedbond-containing acid chloride and/or acid anhydride to act upon thearomatic ring in said polymer block (b). In this connection, thepreferred block copolymer is such that the monomer unit derived from thearomatic vinyl compound in said isobutylene block copolymer has beenmodified preferably by not less than 1% on a molar basis, morepreferably by not less than 5% on the same basis.

The unsaturated bond-containing acid chloride for use in the abovemodification is not particularly restricted provided that it may act onan aromatic ring, thus including methacryloyl chloride, methacryloylbromide, methacryloyl iodide, acryloyl chloride, acryloyl bromide,acryloyl iodide, crotonyl chloride, crotonyl bromide, and crotonyliodide, among others. Among these, methacryloyl chloride is advantageousin terms of commercial availability.

The unsaturated bond-containing acid anhydride is not particularlyrestricted provided that it may act on an aromatic ring, thus includingmaleic anhydride, phthalic anhydride and so forth. Among these, maleicanhydride is particularly preferred from the standpoint of solubility inthe reaction solvent.

These may be used each independently or as a mixture of two or morespecies.

The modification mentioned above can be made by a procedure whichcomprises dissolving the isobutylene block copolymer in a solvent andcarrying out a Friedel-Crafts reaction with said acid anhydride and/oracid chloride in the presence of a Lewis acid. Further, after completionof the polymerization reaction of said isobutylene block copolymer, saidmodification may be made by adding said acid chloride and/or acidanhydride to the polymerization reaction mixture and, if necessary,adding a Lewis acid as well.

By the modification with said acid chloride and/or acid anhydride, thepolymer block composed predominantly of an aromatic vinyl compound canbe provided with at least one unit represented by the following formula(I), on the average.

In the formula, R¹ represents an unsaturated bond-containing univalentorganic group.

By means of the above modification, the molecular chain of theisobutylene block copolymer can be provided with an unsaturated bond.

The number average molecular weight of the unsaturated bond-containingisobutylene polymer (A) is not particularly restricted but is preferably1,000 to 500,000, particularly 2,000 to 400,000. If the number averagemolecular weight is less than 1,000, the necessary mechanical and othercharacteristics will not be sufficiently expressed. If it exceeds500,000, moldability will deteriorate drastically. The number averagemolecular weight is measured by using gel permeation chromatographytechnique. In the gel permeation chromatography measurement, samples areanalyzed by using chloroform, tetrahydrofuran or dimethylformamide as aneluent, polystyrene gel column, and polystyrene standard sample as thecriterion.

Olefinic Resin (B)

The olefinic resin (B) is not particularly restricted insofar as thehitherto-known species can be employed but an olefin homopolymer orcopolymer with the combined ethylene and C₃₋₂₀, α-olefin content being50 to 100 mol % is preferred. Particularly preferred are polyethylenessuch as a homopolymer of ethylene, a copolymer of ethylene with not morethan 5 mol % of an α-olefin monomer, and a copolymer of ethylene withnot more than 1 mol % of a nonolefinic monomer having a functional groupconsisting exclusively of carbon, oxygen and hydrogen atoms(specifically, the so-called low-density polyethylene and high-densitypolyethylene can be mentioned); polypropylenes such as an intrinsicallycrystalline homopolymer of propylene and an intrinsically crystallinecopolymer of propylene and an α-olefin monomer, of which the propyleneunit accounts for not less than 50 mol %.

Furthermore, in terms of effects on the crosslinking of the unsaturatedbond-containing isobutylene polymer, the olefinic resin (B) ispreferably a resin not containing an unsaturated bond.

The formulating level of the olefinic resin (B) per 100 weight parts ofthe unsaturated bond-containing isobutylene polymer (A) is preferably 10to 300 weight parts, more preferably 10 to 200 weight parts, still morepreferably 20 to 200 weight parts. If the formulating level of theolefinic resin (B) exceeds 300 weight parts, the degree of improvementin permanent compression set tends to be insufficient. If it is lessthan 10 weight parts, moldability tends to be sacrificed.

Crosslinking

In order that a more satisfactory permanent compression set may beattained, the thermoplastic elastomer of the invention preferably has acrosslinked polymer structure. It may be an elastomer in which theunsaturated bond-containing isobutylene copolymer (A) as such has beenintermolecularly crosslinked, the olefinic resin (B) as such has beenintermolecularly crosslinked, or the unsaturated bond-containingisobutylene copolymer (A) and olefinic resin (B) have been crosslinkedto each other. However, the structure in which the unsaturatedbond-containing isobutylene copolymer (A) has been crosslinked betweenits molecules is preferred, for a particularly satisfactory permanentcompression set can then be attained.

In the case where the unsaturated bond-containing isobutylene copolymer(A) has an intermolecularly crosslinked structure, the crosslinking ispreferably a crosslinking involving the unsaturated bond contained inthe isobutylene copolymer (A). In this case, the olefinic resin (B) ispreferably not crosslinked.

The above-mentioned crosslinking may be effected in the stage where theunsaturated bond-containing isobutylene polymer (A) and olefinic resin(B) are melt-kneaded together, in a stage preceding the melt-kneading ofthe unsaturated bond-containing isobutylene polymer (A) and olefinicresin (B), or separately after the melt-kneading of the unsaturatedbond-containing isobutylene polymer (A) and olefinic resin (B). However,it is particularly recommendable to carry out the crosslinking,so-called the dynamic crosslinking at melt-kneading of the unsaturatedbond-containing isobutylene polymer (A) and olefinic resin (B), for aparticularly satisfactory permanent compression set can then beobtained.

The means of crosslinking may be a known one and is not particularlyrestricted. As examples, crosslinking by heating and crosslinking withthe aid of a crosslinking agent can be mentioned.

For the crosslinking by heating, the polymer may be heated to about 100°C. to 230° C.

The crosslinking agent for use in said crosslinking reaction with theaid of a crosslinking agent is not particularly restricted insofar asthe polymer may be crosslinked but a hydrosilyl group-containingcompound or a radical crosslinking agent is preferred because thecrosslinking can then be efficiently accomplished by exploiting theunsaturated bond of the isobutylene polymer (A). The hydrosilylgroup-containing compound is particularly beneficial in the case wherethe isobutylene polymer (A) is a polymer terminating in an unsaturatedbond.

The hydrosilyl group-containing compound is not particularly restrictedbut a variety of compounds can be employed. For example, there can beused linear polysiloxanes represented by the general formula (II) or(III):R² ₃SiO—[Si(R²)₂O]_(a)—[Si(H)(R³)O]_(b)—[Si(R³)(R⁴)O]_(c)—SiR² ₃  (II)HR² ₂SiO—[Si(R²)₂O]_(a)—[Si(H)(R³)O]_(b)—[Si(R³)(R⁴)O]_(c)—SiR²₂H  (III)in the formula, R² and R³ each independently represents an alkyl groupof 1 to 6 carbon atoms or a phenyl group; R⁴ represents an alkyl oraralkyl group of 1 to 10 carbon atoms; a, b, and c are integerssatisfying the relations 0≦a≦100, 2≦b≦100, and 0≦c≦100, respectively andcyclic siloxanes represented by the general formula (IV):

in the formula, R⁵ and R⁶ each independently represents an alkyl groupof 1 to 6 carbon atoms or a phenyl group; R⁷ represents an alkyl oraralkyl group of 1 to 10 carbon atoms; d, e, and f are integerssatisfying the relations 0≦d≦8, 2≦e≦10 and 0≦f≦8, respectively, andfurther satisfying the relation 3≦d+e+f≦10. Furthermore, among the abovehydrosilyl (Si—H) group-containing compounds, those compounds which maybe represented by the following general formula (V) are particularlypreferred in terms of compatibility between the components (A) and (B).

In the formula, g and h are integers satisfying the relations 2≦g+h≦50,2≦g, and 0≦h; R⁸ represents a hydrogen atom or a methyl group; R⁹represents a hydrocarbon group of 2 to 20 carbon atoms and mayoptionally have one or more aromatic rings; i is an integer of 0≦i≦5.

While the unsaturated bond-containing isobutylene polymer (A) and thehydrosilyl group-containing compound may be admixed in any desiredratio, it is preferable from curability points of view that the molarratio of the unsaturated bond to the hydrosilyl group should be withinthe range of 5 to 0.2. The range of 2.5 to 0.4 is still more preferred.If the molar ratio referred to above exceeds 5, curability tends to beinsufficient so that occasionally only a tacky product of low strengthmay be obtained on curing. If the ratio is less than 0.2, many activehydrosilyl groups will remain after curing so that the cured product maydevelop cracks and voids, thus being deficient in homogeneity andstrength.

The crosslinking reaction of the unsaturated bond-containing isobutylenepolymer (A) and the hydrosilyl group-containing compound proceeds as thetwo materials are blended and heated but in order to hasten thereaction, a hydrosilylation catalyst can be added. The hydrosilylationcatalyst that can be used for this purpose is not particularlyrestricted but includes radical initiators, such as organic peroxidesand azo compounds, and transition metal catalysts, among others.

The radical initiator referred to above is not particularly restrictedbut includes dialkyl peroxides, such as di-t-butyl peroxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, dicumyl peroxide,t-butylcumyl peroxide, α,α′-bis(t-butylperoxy)isopropylbenzene, etc.;diacyl peroxides, such as benzoyl peroxide, p-chlorobenzoyl peroxide,m-chlorobenzoyl peroxide, 2, 4-dichlorobenzoyl peroxide, lauroylperoxide, etc.; peracid esters, such as t-butyl perbenzoate;peroxydicarbonates, such as diisopropyl peroxydicarbonate,di-2-ethylhexyl peroxydicarbonate, etc.; and peroxyketals, such as1,1-di(t-butylperoxy)cyclohexane,1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, etc. and so forth.

The azo compound referred to above is not particularly restricted butincludes 2,2′-azobis-isobutyronitrile,2,2′-azobis-2-methylbutyronitrile, 1,1′-azobis-1-cyclohexanecarbonitrile and so forth.

The transition metal catalyst referred to above is not particularlyrestricted but includes platinum metal, a solid platinum dispersion on amatrix such as alumina, silica, carbon black, or the like,chloroplatinic acid, complexes of chloroplatinic acid with alcohols,aldehydes or ketones, platinum-olefin complexes,platinum(O)-dialkenyltetramethyldisiloxanes, and so forth. As transitionmetal catalysts other than platinum compounds, there may be mentionedRhCl(PPh₃)₃, RhCl₃, RuCl₃, IrCl₃, FeCl₃, AlCl₃, PdCl₂.H₂O, NiCl₂, andTiCl₄, by way of example.

These hydrosilylation catalysts can be used each independently or in acombination of two or more species.

The level of use of the hydrosilylation catalyst is not particularlyrestricted but, for each mol of the unsaturated bond in component (A),the catalyst is used preferably within the range of 10⁻¹ to 10⁻⁸ mol,more preferably within the range of 10⁻³ to 10⁻⁶ mol. If the amount ofthe catalyst is less than 10⁻⁸ mol, the curing reaction may not proceedsufficiently depending on cases. On the other hand, because anyhydrosilylation catalyst is expensive, it is advisable to refrain fromusing the catalyst in excess over 10⁻¹ mol.

Among the above-mentioned catalysts, platinum-vinylsiloxane is the mostadvantageous in terms of compatibility, crosslinking efficiency, andscorch stability.

The radical crosslinking agent which can be used as the crosslinkingagent according to the invention is not particularly restricted but anorganic peroxide, among others, is generally used. The organic peroxideis not particularly restricted but includes dialkyl peroxides, such asdi-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, dicumyl peroxide,t-butylcumyl peroxide, α,α′-bis(t-butylperoxy)isopropylbenzene, etc.;diacyl peroxides, such as benzoyl peroxide, p-chlorobenzoyl peroxide,m-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroylperoxide, etc.; peracid esters, such as t-butyl perbenzoate etc.;peroxydicarbonates, such as diisopropyl peroxydicarbonate,di-2-ethylhexyl peroxydicarbonate, etc.; and peroxyketals, such as1,1-di(t-butylperoxy)cyclohexane,1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, etc. and so forth.Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne are preferred in terms ofodor, coloring potential, and scorch stability.

The level of use of the organic peroxide is preferably 0.5 to 5 weightparts per 100 weight parts of the isobutylene polymer (A) at the time ofaddition of the organic peroxide.

In the case where an organic peroxide is used as the crosslinking agent,an auxiliary crosslinking agent having an ethylenically unsaturatedgroup may be further formulated. The auxiliary crosslinking agent havingan ethylenically unsaturated group includes polyfunctional vinylmonomers, such as divinylbenzene, triallyl cyanurate, etc., andpolyfunctional methacrylate monomers, such as ethylene glycoldimethacrylate, diethylene glycol dimethacrylate, triethylene glycoldimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropanetrimethacrylate, allyl methacrylate and so forth. These may be used eachindependently or in a combination of two or more species. By using sucha compound as above in combination with said organic peroxide, a moreuniform and efficient crosslinking reaction can be expected.

Among the above compounds, ethylene glycol dimethacrylate andtriethylene glycol dimethacrylate are preferred because they are notonly easy to handle but also have a solubilizing effect on the peroxideand act as an auxiliary dispersant for the peroxide, thus making theeffect of crosslinking uniform and pronounced and, hence, athermoplastic elastomer balanced in hardness and rubber-like elasticityis more certainly obtained.

The level of addition of said auxiliary crosslinking agent is preferablywithin the range of 0.5 to 10.0 weight parts per 100 weight parts of theisobutylene polymer (A) at the time of addition. If the level ofaddition of the auxiliary crosslinking agent is lower than 0.5 weightparts, the contributory effect on crosslinking will not be obtained. Ifit exceeds 10 weight parts, the auxiliary crosslinking agent itselfundergoes gelation to adversely affect physical properties and increasethe cost.

Optional Ingredients

In addition to the isobutylene polymer (A) and olefinic resin (B), thethermoplastic elastomer composition of the invention preferably containsa plasticizer (C) for improved moldability and flexibility.

As the plasticizer (C), the mineral oil for use in the processing ofrubber or a liquid or low-molecular weight synthetic softening agent canbe used.

The mineral oil includes paraffinic oils, naphthenic oils, and aromatichigh-boiling petroleum fractions, although paraffinic and naphthenicoils which do not interfere with the crosslinking reaction arepreferred.

The liquid or low-molecular weight synthetic softening agent is notparticularly restricted but includes polybutene, hydrogenatedpolybutene, liquid polybutadiene, hydrogenated liquid polybutadiene,polyisobutylene, and poly(α-olefins), among others.

These species of plasticizer (C) may be used each independently or in asuitable combination.

The formulating level of said plasticizer (C) is preferably 1 to 300weight parts per 100 weight parts of the unsaturated bond-containingisobutylene polymer (A). If the formulating level exceeds 300 weightparts, mechanical strength and moldability tend to be adverselyaffected.

The most desirable formulation for the thermoplastic elastomercomposition of the invention, based on 100 weight parts of saidunsaturated bond-containing isobutylene polymer (A), is the olefinicresin (B): 20 to 200 weight parts and the plasticizer (C): 10 to 300weight parts.

The thermoplastic elastomer composition of the invention may be furthersupplemented with various other ingredients or additives suited to thespecific characteristics required of each end use within the range notadversely affecting physical properties; for example various reinforcingagents, fillers, elastomers such as styrene-butadiene-styrene blockcopolymer (SBS) and styrene-isoprene-styrene block copolymer (SIS), thecorresponding hydrogenated styrene-ethylenebutylene-styrene blockcopolymer (SEBS) and styrene-ethylenepropylene-styrene block copolymer(SEPS), etc., hindered phenol or hindered amine series antioxidants,ultraviolet absorbers, light stabilizers, pigments, surfactants, flameretardants, fillers, reinforcing agents, and so forth, each in anappropriate proportion.

Method of Producing the Thermoplastic Elastomer of the Invention

The method of producing the thermoplastic elastomer composition of theinvention is not particularly restricted but may be any method thatprovides for uniform blending of the unsaturated bond-containingisobutylene polymer (A), olefinic resin (B), and said optionalcomponents.

In the case where the thermoplastic elastomer composition of theinvention is to be produced by conducting a crosslinking reaction at thestage of melt-kneading of said unsaturated bond-containing isobutylenepolymer (A) and olefinic resin (B), any of following procedures can beused with advantage.

The procedure using a closed type mill or a batch mill, such as LaboPlastomill, Banbury mixer, kneader, roll mill or the like comprisesmelt-kneading all the component materials but the crosslinking agent andauxiliary crosslinking agent until a homogeneous mixture is obtained,adding the crosslinking agent, optionally together with the auxiliarycrosslinking agent, and allowing the crosslinking reaction to proceedfar enough until the melt-kneading is no longer feasible.

The procedure employing a continuous melt-kneading machine, such as asingle-screw extruder, a twin-screw extruder or the like, comprisesmelt-kneading all the component materials but the crosslinking agent andauxiliary crosslinking agent until a homogeneous mixture is obtained,pelletizing the mixture, dry-blending the pellets with the crosslinkingagent, optionally together with the auxiliary crosslinking agent, andfurther melt-kneading the dry blend by means of a melt-kneading machine,such as an extruder, to give a thermoplastic elastomer composition inwhich the unsaturated bond-containing isobutylene polymer (A) and/orolefinic resin (B) has been dynamically crosslinked. An alternativemethod comprises melt-kneading all the component materials but thecrosslinking agent and auxiliary crosslinking agent with a melt-kneadingmachine such as an extruder, adding the crosslinking agent, optionallytogether with the auxiliary crosslinking agent, partway of the cylinderof the extruder, and melt-kneading the mixture further to give athermoplastic elastomer composition in which the unsaturatedbond-containing isobutylene polymer (A) and/or the olefinic resin (B)has been dynamically crosslinked.

In carrying out the above procedure for concurrent melt-kneading andcrosslinking, the melt-kneading is preferably carried out under heatingat about 140 to 210° C.

For producing the thermoplastic elastomer composition of the inventionby causing the unsaturated bond-containing isobutylene polymer (A) tocrosslink in advance and blending the crosslinked polymer with theolefinic resin (B), the following procedure, for instance, can be usedwith advantage.

Thus, the thermoplastic elastomer composition of the invention can beproduced by adding the crosslinking agent, optionally together with theauxiliary crosslinking agent, and other additive materials to theunsaturated bond-containing isobutylene polymer (A), kneading themixture thoroughly at a suitable temperature by means of a kneader whichis conventionally used in the manufacture of crosslinked rubberproducts, feeding the kneaded mass to a hot-press machine or the likeand allowing it to crosslink at a suitable temperature for a suitabletime, cooling the reaction mixture, and crushing it to give acrosslinked isobutylene polymer (A), and melt-kneading this crosslinkedpolymer and the olefinic resin (B) together to give the thermoplasticelastomer composition of the invention.

In this connection, as the method of melt-kneading the crosslinkedpolymer of unsaturated bond-containing isobutylene polymer (A) with theolefinic resin (B), any of the known techniques heretofore in use forthe production of thermoplastic resin or thermoplastic elastomercompositions can be employed and carried into practice by using amelt-kneading machine such as Labo Plastomill, Banbury mixer,single-screw extruder, twin-screw extruder or the like. The preferredmelt-kneading temperature is 140 to 210° C.

For producing the thermoplastic elastomer composition of the inventionby kneading the unsaturated bond-containing isobutylene polymer (A) andolefinic resin (B) together and, then, carrying out a crosslinkingreaction independently, the procedures mentioned above can be used incombination according to need.

Uses for the Thermoplastic Elastomer of the Invention

The thermoplastic elastomer composition of the present invention can bemolded by the molding technology and device in routine use forthermoplastic resin compositions, that is to say by melt-molding, suchas extrusion molding, injection molding, press molding, blow molding,and so forth.

Since the thermoplastic elastomer composition of the invention has verysatisfactory moldability, permanent compression set and vibrationdamping properties, it can be used with advantage in a variety ofapplications, such as sealing materials, e.g. packing, sealants,gaskets, plugs, etc., CD dampers, architectural dampers, vibrationdamping materials for automobiles and other road vehicles, householdelectrical appliances, etc., vibration preventing materials, carupholstery, cushioning materials, sundry goods, electrical parts,electronic parts, members of sporting goods, grips or cushioning pads,electric conductor sheaths, packaging materials, various vessels, andstationery articles.

BEST MODE FOR CARRYING OUT THE INVENTION

The following examples illustrate the present invention in furtherdetail without defining the scope of the invention.

Before presenting the examples, the various methods of determinationsand various evaluation methods used are described.

Hardness

In accordance with JIS A 6352; a 12.0 mm-thick pressed sheet was used asthe testpiece.

Permanent Compression Set

In accordance with JIS K 6262; a 12.0 mm-thick pressed sheet was used asthe testpiece. The measuring conditions were 100° C.×22 hr and 25%deformation.

Dynamic Viscoelasticity

In accordance with JIS K 6394 (Testing Methods for Dynamic Properties ofVulcanized Rubber and Thermoplastic Rubber); a testpiece measuring 6 mmlong×5 mm wide×2 mm thick was cut out and using the dynamicviscoelasticity measuring apparatus DVA-200 (manufactured by ITInstrumental Control), the loss tangent tan δ value was determined. Themeasuring frequency was 0.5 Hz.

Melting Viscosity

Test conditions: measured by using a capillary rheometer (manufacturedby Toyo Seiki Seisaku-sho) with a die radius of 1 mm at a testingtemperature of 170° C.

Thermoplasticity

The testpiece was milled with Labo Plastomill (manufactured by ToyoSeiki Seisaku-sho) set to 170° C. and it was investigated whether themelt could be remolded.

-   ◯; Plasticized by heating at 170° C.; The surface condition of the    resulting sheet was satisfactory.-   Δ; Plasticized by heating at 170° C.; The surface condition of the    resulting sheet was not satisfactory.-   X; Not plasticized by heating at 170° C.

The abbreviations used for various materials in the following examplesand comparative examples and the particulars of each material are givenbelow.

-   -   Component (A): f-SIBS: a polystyrene-polyisobutylene-polystyrene        triblock copolymer having a methacryloyl group pendant from the        molecular chain (prepared in Production Example 2 below)    -   Component (A): ARSIBS: a polystyrene-polyisobutylene-polystyrene        tribldck copolymer having an allyl group at the molecular chain        terminus (prepared in Production Example 3 below)    -   Component (A): ARPIB: a polyisobutylene having an allyl group at        the molecular chain terminus, EP 600A, product of Kaneka        Corporation.    -   Component (B) HDPE: a high-density polyethylene, product of        Mitsui Petrochemical (™Hizex 8000F)    -   Component (B) PP1: a polypropylene, product of Grand Polymer        (™Grand Polypro J300)    -   Component (B) PP2: a polypropylene: product of Mitsui Chemical        (™Hipol J300)    -   Component (B): PP3: a polypropylene, product of Grand Polymer        (™Grand Polypro J709W)    -   IIR: butyl rubber, product of JSR (™Butyl065)    -   SIBS: a polystyrene-polyisobutylene-polystyrene triblock        copolymer having no unsaturated bond    -   Component (C): plasticizer: a paraffinic process oil, product of        Idemitsu Petrochemical (™Diana Process Oil PW-90)    -   Crosslinking agent 1: 2,5-dimethyl-2,5-di(t-butylperoxy)hexane,        product of Nippon Oils and Fat (™Perhexa 25B)    -   Crosslinking agent 2: a reaction-type brominated alkylphenol        formaldehyde compound, product of Taoka Chemical Company        (™Tackirol 250-1)    -   Crosslinking agent 3: a linear siloxane having an average of 5        hydrosilyl groups and an average of 5 α-methylstyrene groups per        molecule    -   Auxiliary crosslinking agent 1: ethylene glycol dimethacrylate,        product of Kanto Chemical    -   Auxiliary crosslinking agent 2: zinc oxide    -   Auxiliary crosslinking agent 3: stearic acid    -   Hydrosilylation catalyst:        platinum(O)-1,1,3,3-tetramethyl-1,3-diallyldisiloxane complex,        1% solution in xylene

PRODUCTION EXAMPLE 1

[Production of a Polystyrene-Polyisobutylene-Polystyrene TriblockCopolymer not Containing an Unsaturated Bond]

The polymerization vessel in a 2 L separable flask, after nitrogenpurging, was charged with 456.1 mL of n-hexane (dried with molecularsieves) and 656.5 ml of butyl chloride (dried with molecular sieves)using an injection syringe and the polymerizaiton vessel was cooled byimmersion in a dry ice/methanol bath at −70° C. Then, a Teflon liquiddelivery tube was connected to a pressure-resisting glass liquefactionsampling tube equipped with a 3-way cock and containing 232 mL (2871mmol) of isobutylene monomer and the isobutylene monomer was deliveredunder nitrogen pressure to the polymerization vessel. Then, 0.647 g (2.8mmol) of p-dicumyl chloride and 1.22 g (14 mmol) ofN,N-dimethylacetamide were added, further followed by addition of 8.67mL (79.1 mmol) of titanium tetrachloride. The reaction mixture wasstirred at the same temperature for 1.5 hours after the start ofpolymerization and about 1 mL of the polymer slurry was withdrawn as asample. Then, a mixed solution composed of 77.9 g (748 mmol) of styrenemonomer, 23.9 mL of n-hexane, and 34.3 mL of butyl chloride, cooled to−70° C. in advance, was fed to the polymerization vessel. Forty-fiveminutes following addition of the above mixed solution, about 40 mL ofmethanol was added to the reaction mixture to terminate the reaction.

After the solvent and the like were distilled off from the reactionmixture, the residue was dissolved in toluene and washed with twoportions of water. The toluene solution was poured in a large quantityof methanol to precipitate the polymer and the polymer thus Obtained wasdried in vacuo at 60° C. for 24 hours to recover the objective blockcopolymer. The molecular weight of this polymer was determined by gelpermeation chromatography (GPC). Whereas the isobutylene polymer priorto addition of styrene had an Mn value of 50,000 and an Mw/Mn ratio of1.40, the block copolymer obtained after the polymerization of styrenehad an Mn value of 67,000 and an Mw/Mn value of 1.50.

PRODUCTION EXAMPLE 2

[Production of a Polystyrene-Polyisobutylene-Polystyrene TriblockCopolymer Having a Methacryloyl Group Pendant from the Molecular Chain(f-SIBS)]

A 2 L separable flask was charged with 75 g of thepolystyrene-polyisobutylene-polystyrene triblock copolymer prepared inProduction Example 1 (styrene content 30%, the number of mols of thestyrene unit: 0.216 mol), followed by nitrogen purging. Using aninjection syringe, 1200 mL of n-hexane (dried with molecular sieves) and1800 mL of butyl chloride (dried with molecular sieves) were added.Then, using a syringe, 30 g (0.291 mol) of methacryloyl chloride wasadded. Finally, with the solution under stirring, 39.4 g (0.295 mol) ofaluminum trichloride was added so as to initiate the reaction. At 30minutes following the start of reaction, about 1000 ml of water wasadded to the reaction mixture with vigorous stirring to terminate thereaction.

The reaction mixture was washed with a large quantity of water at least5 times. Then, a large quantity of a solvent mixture of methanol andacetone (1:1, vt/vt) was gently added dropwise to precipitate thepolymer and the polymer thus obtained was dried in vacuo at 60° C. for24 hours to give the objective block copolymer.

PRODUCTION EXAMPLE 3

[Production of a Polystyrene-Polyisobutylene-Polystyrene TriblockCopolymer Having an Allyl Group at the Molecular Chain Terminus(ARSIBS)]

The polymerization vessel of a 2 L separable flask was subjected tonitrogen purging, and using an injection syringe, 456.1 mL of n-hexane(dried with molecular sieves) and 656.5 mL of butyl chloride (dried withmolecular sieves) were added. The polymerization vessel was cooled byimmersion in a dry ice/methanol bath at −70° C. Then, a Teflon liquiddelivery tube was connected to a pressure-resisting glass liquefactionsampling tube equipped with a 3-way cock and containing 201 mL (2132mmol) of isobutylene monomer and the isobutylene monomer was deliveredunder nitrogen pressure to the polymerization vessel. Then, 2.6 g (11.2mmol) of p-dicumyl chloride and 1.22 g (14 mmol) ofN,N-dimethylacetamide were added, further followed by addition of 9.9 mL(90.0 mmol) of titanium tetrachloride. The reaction mixture was stirredat the same temperature for 1.5 hours after the start of polymerizationand about 1 mL of the polymer slurry was withdrawn as a sample. Then, amixed solution composed of 52 g (499 mmol) of styrene monomer, 23.9 mLof n-hexane, and 34.3 mL of butyl chloride, cooled to −70° C. inadvance, was added to the polymerization vessel. Forty-five minutesfollowing addition of the above mixed solution, about 12 mL (10.0 mmol)of allyltrimethylsilane was added to the vessel. The reaction mixturewas stirred at the prevailing temperature for 60 minutes, at the end ofwhich time about 40 mL of methanol was added so as to terminate thereaction.

After the solvent and the like were distilled off from the reactionmixture, the residue was dissolved in toluene and washed with twoportions of water. This toluene solution was poured in a large quantityof methanol to precipitate the polymer and the polymer thus obtained wasdried in vacuo at 60° C. for 24 hours to recover the objective blockcopolymer. The molecular weight of this polymer was measured by gelpermeation chromatography (GPC). Whereas the isobutylene polymer priorto addition of styrene had an Mn value of 10500 and an Mw/Mn ratio of1.40, the block copolymer obtained after the polymerization of styrenehad an Mn value of 15000 and an Mw/Mn value of 1.50.

EXAMPLE 1

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the f-STBS prepared in Production Example 2, HDPE, andplasticizer were melt-kneaded in the ratio indicated in Table 1 for 5minutes. Then, crosslinking agent 1 and auxiliary crosslinking agent 1were added in the proportions indicated in Table 1 and the melt-kneadingfor dynamic crosslinking was carried out at 180° C. until the torquevalue had reached a peak level. The resulting thermoplastic elastomercomposition could be easily molded into a sheet by using the SintohMetal's hot-press at 180° C. The hardness, permanent compression set,and thermoplasticity of the sheet were measured by the methods describedabove. The physical values of the sheet are presented in Table 1.

EXAMPLE 2

Except that the formulating level of the plasticizer was changed to 100weight parts, the procedure of Example 1 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values of the sheet are presented in Table 1.

EXAMPLE 3

Except that the formulating level of HDPE was changed to 35 weightparts, the procedure of Example 1 was otherwise repeated to mold theresin composition into a sheet and evaluate its physical properties. Thephysical values of the sheet are presented in Table 1.

EXAMPLE 4

Except that 15 weight parts of HDPE and 40 weight parts of PP1 were usedin lieu of 50 weight parts of HDPE, the procedure of Example 1 wasotherwise repeated to mold the resin composition into a sheet andevaluate its physical properties. The physical values of the sheet arepresented in Table 1.

EXAMPLE 5

Except that 50 weight parts of PP1 was used in lieu of HDPE, theprocedure of Example 1 was otherwise repeated to mold the resincomposition into a sheet and evaluate its physical properties. Thephysical values of the sheet are presented in Table 1.

COMPARATIVE EXAMPLE 1

The SIBS prepared in Production Example 1 was melt-kneaded by LaboPlastomill at 180° C. for 10 minutes and, then, molded into a sheet at180° C. The hardness, permanent compression set, and thermoplasticity ofthe sheet were measured by the methods described hereinbefore. Thephysical values of the sheet are presented in Table 2.

COMPARATIVE EXAMPLE 2

The f-SIBS prepared in Production Example 2 was melt-kneaded with LaboPlastomill at 180° C. for 10 minutes, after which crosslinking agent 1and auxiliary crosslinking agent 1 were added in the proportionsindicated in Table 2, and the melt-kneading was further continued at180° C. The kneaded mass was then molded into a sheet at 180° C. Thehardness, permanent compression set, and thermoplasticity of the sheetwere measured by the methods described hereinbefore. The physical valuesof the sheet are presented in Table 2.

COMPARATIVE EXAMPLE 3

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the SIBS prepared in Production Example 1, HDPE, andplasticizer were melt-kneaded in the ratio indicated in Table 2 for 5minutes. Then, crosslinking agent 1 and auxiliary crosslinking agent 1were added in the proportions indicated in Table 2 and the melt-kneadingfor dynamic crosslinking was carried out at 180° C. until the torquevalue had reached a peak level. The resulting composition was moldedinto a sheet by Shintoh Metal's hot-press and the hardness, permanentcompression set, and thermoplasticity of the sheet were measured by themethods described hereinbefore. The physical values of the sheet arepresented in Table 2.

COMPARATIVE EXAMPLE 4

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the SIBS prepared in Production Example 1 and IIR weremelt-kneaded in the ratio indicated in Table 2 for 5 minutes. Then,crosslinking agent 2, auxiliary crosslinking agent 2, and auxiliarycrosslinking agent 3 were added in the proportions indicated in Table 2and the melt-kneading for dynamic crosslinking was carried out at 180°C. until the torque value had reached a peak level. The resultingcomposition was molded into a sheet by using Shintoh Metal's hot-pressand the hardness, permanent compression set, and thermoplasticity of thesheet were measured by the methods described hereinbefore. The physicalvalues of the sheet are presented in Table 2.

COMPARATIVE EXAMPLE 5

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the SIBS prepared in Production Example 1 and PP1 weremelt-kneaded in the ratio indicated in Table 2 for 5 minutes to give adesired composition. The resulting composition was molded into a sheetby using Shintoh Metal's hot-press and the hardness, permanentcompression set, and thermoplasticity of the sheet were measured by themethods described hereinbefore. The physical values of the sheet arepresented in Table 2.

COMPARATIVE EXAMPLE 6

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the SIBS prepared in Production Example 1, PP1 and plasticizerwere melt-kneaded in the ratio indicated in Table 2 for 5 minutes togive a desired composition. The resulting composition was molded into asheet by using Shintoh Metal's hot-press and the hardness, permanentcompression set, and thermoplasticity of the sheet were measured by themethods described hereinbefore. The physical values of the sheet arepresented in Table 2.

COMPARATIVE EXAMPLE 7

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the SIBS prepared in Production Example 1, PP1 and plasticizerwere melt-kneaded in the ratio indicated in Table 2 for 5 minutes togive a desired composition. The resulting composition was molded into asheet by using Shintoh Metal's hot-press and the hardness, permanentcompression set, and thermoplasticity of the sheet were measured by themethods described hereinbefore. The physical values of the sheet arepresented in Table 2.

COMPARATIVE EXAMPLE 8

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the ARSIBS prepared in Production Example 3, PP1 andplasticizer were melt-kneaded in the ratio indicated in Table 2 for 5minutes to give a desired composition. The resulting composition wassubjected to molding using Shintoh Metal's hot-press, however, it couldnot be molded. The thermoplasticity of the composition was measured bythe methods described hereinbefore. The result of the composition ispresented in Table 2.

COMPARATIVE EXAMPLE 9

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to180° C., the ARPIB, PP1 and plasticizer were melt-kneaded in the ratioindicated in Table 2 for 5 minutes to give a desired composition. Theresulting composition was subjected to molding using Shintoh Metal'shot-press, however, it could not be molded. The thermoplasticity of thecomposition was measured by the methods described hereinbefore. Theresult of the composition is presented in Table 2.

TABLE 1 Ex. 1 2 3 4 5 f-SIBS (Weight parts) 100 100 100 100 100 HDPE(Weight parts) 50 50 35 15 — PP1 (Weight parts) — — — 40 50 Plasticizer(Weight parts) 60 100 60 60 60 Crosslinking agent 1 3 3 3 3 3 (Weightparts) Auxiliary crosslinking agent 1 5 5 5 5 5 (Weight parts) Hardness80 67 77 64 92 (JIS A: immediately after press) Parmanent compressionset (%) 50 35 52 58 78 Thermoplasticity ◯ ◯ ◯ ◯ ◯

TABLE 2 Compar. Ex. 1 2 3 4 5 6 7 8 9 SIBS (Weight parts) 100  — 100 100  100  100  100  — — f-SIBS (Weight parts) — 100  — — — — — — —ARSIBS (Weight parts) — — — — — — — 100 — ARPIB (Weight parts) — — — — —— — — 100 HDPE (Weight parts) — — 50 — — — — — — IIR (Weight parts) — —— 100  — — — — — PPI (Weight parts) — — — — 25 35 25  25  25 Plasticizer(Weight parts) — — 60 — — 60 100  100 100 Crosslinking agent 1  3  3  3— — — — — — (Weight parts) Crosslinking agent 2 — — — 10 — — — — —(Weight parts) Auxiliary crosslinking agent 1  5  5  5 — — — — — —(Weight parts) Auxiliary crosslinking agent 2 — — —  5 — — — — — (Weightparts) Auxiliary crosslinking agent 3 — — —  1 — — — — — (Weight parts)Hardness 47 72 44 35 75 56 43 Not Not (JIS A: immediately after press)molded molded Parmanent compression set (%) 87 68 94 68 95 85 95Thermoplasticity ◯ X ◯ Δ ◯ ◯ ◯ ◯ ◯

The thermoplastic elastomer composition of the invention, viz. Examples1 to 5, showed low compressive set values as compared with the use ofSIBS alone, thus being superior in permanent compression setcharacteristic while retaining the characteristics of an isobutyleneblock copolymer.

EXAMPLE 6

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to170° C., the ARSIBS prepared in Production Example 3 and PP2 weremelt-kneaded together for 3 minutes. Then, crosslinking agent 3 wasadded in the proportion indicated in Table 3 and after addition ofcomponent (C) and 50 μl of hydrosilylation catalyst, the mixture wasmelt-kneaded at 170° C. for dynamic crosslinking until the torque valuehad reached a peak level. The resulting thermoplastic elastomercomposition could be easily molded into a sheet with Shintoh Metal'shot-press at 180° C. The hardness, permanent compression set, andthermoplasticity of the sheet were measured by the methods describedhereinbefore. The physical values of the sheet are presented in Table 3.

EXAMPLE 7

Except that the formulating level of component (C) was changed to 150weight parts, the procedure of Example 6 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 3.

EXAMPLE 8

Except that the formulating level of PP2, i.e. component (B), waschanged to 35 weight parts, the procedure of Example 6 was otherwiserepeated to mold the resin composition into a sheet and evaluate itsphysical properties. The physical values are presented in Table 3.

EXAMPLE 9

Except that PP3 was used for component (B) and that the formulatinglevel of component (C) was changed to 50 weight parts, the procedure ofExample 6 was otherwise repeated to mold the resin composition into asheet and evaluate its physical properties. The physical values arepresented in Table 3.

EXAMPLE 10

Except that PP3 was used for component (B), the procedure of Example 6was otherwise repeated to mold the resin composition and the hardness,permanent compression set, thermoplasticity, dynamic viscoelasticity,and melting viscosity were determined by the methods describedhereinbefore. The physical values thus found are presented in Tables 3to 5.

EXAMPLE 11

Except that the formulating level of component (C) was changed to 200weight parts, the procedure of Example 10 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 3.

EXAMPLE 12

Except that the formulating level of component (B) was changed to 35weight parts, the procedure of Example 10 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 3.

EXAMPLE 13

Except that the formulating level of component (B) was changed to 50weight parts, the procedure of Example 10 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Tables 3 to 5.

EXAMPLE 14

Except that the formulating level of component (C) was changed to 0weight part, the procedure of Example 13 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 3.

EXAMPLE 15

Except that HDPE was used for component (B), the procedure of Example 6was otherwise repeated to mold the resin composition into a sheet andevaluate its physical properties. The physical values are presented inTable 3.

EXAMPLE 16

Except that the formulating level of component (B) was changed to 100weight parts, the procedure of Example 13 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Tables 3 to 5.

EXAMPLE 17

Except that the formulating level of component (B) was changed to 250weight parts, the procedure of Example 13 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 3.

COMPARATIVE EXAMPLE 10

A resin composition comprising AES Japan's Santoplain 211-45, anolefinic thermoplastic elastomer was molded and the dynamicviscoelasticity and melting viscosity of the product were determined bythe methods described hereinbefore. The physical values are shown inTables 4, 5 and 7.

TABLE 3 Ex. 6 7 8 9 10 11 12 13 14 15 16 17 Component (A) ARSIBS (Weight100 100 100 100 100 100 100 100 100 100 100 100 parts) Component (B) PP2(Weight parts) 25 25 35 — — — — — — — — — Component (B) PP3 (Weightparts) — — — 25 25 25 35 50 50 — 100 250 Component (B) HDPE (Weightparts) — — — — — — — — — 25 — — Component (C) PW-90 (Weight 100 150 10050 100 200 100 100 0 100 100 100 parts) Crosslinking agent 3 (Weight 9 99 9 9 9 9 9 9 9 9 9 parts) Hydrosilylation catalyst (ul) 50 50 50 50 5050 50 50 50 50 50 50 Parmanent compression set (%) 22 25 39 29 20 27 3240 40 25 52 66 Hardness (JIS A: immediately after 51 41 58 74 52 43 6261 90 42 89 90 press) Thermoplasticity ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯

TABLE 4 Temperature Ex. Ex. Ex. Ex. Ex. Ex. Compar. (° C.) 10 13 16 1827 28 Ex. 10 −65 0.42 0.16 0.27 0.47 0.20 0.21 0.14 −45 0.75 0.45 0.400.69 0.35 0.41 0.32 −25 0.29 0.25 0.20 0.32 0.27 0.20 0.17

TABLE 5 Viscosity (poise) Shear Compar. rate (/s) Ex. 10 Ex. 13 Ex. 16Ex. 27 Ex. 28 Ex. 10 12.16 11050 25620 36500 38500 15310 70500 1216 470870 1080 1170 920 3790

The thermoplastic elastomer composition of the invention, specificallyExamples 6, 7, 8, 9, 10 and 11, varied in hardness over a broad range of41 to 74 (JIS A) including the hardness value of the isobutylene blockcopolymer SIBS as used alone in Comparative Example 1 (JIS A:47), andyet showed appreciably low permanent compression set values, i.e. of theorder of 20%, as compared with SIBS as it is used alone. It is alsoapparent that compared with the case in which the crosslinking productof SIBS and IIR shown in Comparative Example 4 was used, thethermoplastic elastomer composition of the invention is superior in theparameter of permanent compression set.

Comparison of Example 10 with Comparative Example 10 for dynamicviscoelasticity reveals that Example 10 according to the invention has ahigher tan δ value. The parameter tan δ represents the attenuationdamping property of a vibration damping material and the higher the tana value is, the more pronounced is the attenuation damping properties.In other words, Example 10 is superior in vibration damping property.

Comparison of Example 10 with Comparative Example 10 reveals thatExample 10 is lower in viscosity, suggesting that it is superior inextrusion moldability and injection moldability.

EXAMPLE 18

Using Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho) set to170° C., ARPIB, PP2, and component (C) were melt-kneaded in the ratioindicated in Table 6 for 3 minutes, at the end of which time thecrosslinking agent 3 was added in the proportion indicated in Table 6.Then, 50 μl of the hydrosilylation catalyst was added and themelt-kneading was further carried out at 170° C. for dynamiccrosslinking until the torque value had reached a peak level. Theresulting thermoplastic elastomer composition could be easily moldedinto a sheet by using Shintoh Metal's hot-press at 180° C. The hardness,permanent compression set, and thermoplasticity of the sheet thusobtained were determined by the methods described hereinbefore. Thephysical values of the sheet are presented in Table 6. The dynamicviscoelasticity of the sheet was also determined by the method describedhereinbefore. The results are presented in Table 4.

EXAMPLE 19

Except that the formulating level of component (C) was changed to 100weight parts, the procedure of Example 18 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 6.

EXAMPLE 20

Except that the formulating level of component (C) was changed to 150weight parts, the procedure of Example 18 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 6.

EXAMPLE 21

Except that the formulating level of component (C) was changed to 200weight parts, the procedure of Example 18 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 6.

EXAMPLE 22

Except that the formulating level of PP2 was changed to 35 weight parts,the procedure of Example 19 was otherwise repeated to mold the resincomposition into a sheet and evaluate its physical properties. Thephysical values are presented in Table 6.

EXAMPLE 23

Except that the formulating level of component (C) was changed to 250weight parts, the procedure of Example 19 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 6.

EXAMPLE 24

Except that the formulating level of PP2 was changed to 50 weight parts,the procedure of Example 21 was otherwise repeated to mold the resincomposition into a sheet and evaluate its physical properties. Thephysical values are presented in Table 6.

EXAMPLE 25

Except that PP3 was used in lieu of PP2 for component (B), the procedureof Example 19 was otherwise repeated to mold the resin composition intoa sheet and evaluate its physical properties. The physical values arepresented in Table 6.

EXAMPLE 26

Except that the formulating level of component (C) was changed to 150weight parts, the procedure of Example 25 was otherwise repeated to moldthe resin composition into a sheet and evaluate its physical properties.The physical values are presented in Table 6.

EXAMPLE 27

Except that the formulating level of PP3 was changed to 50 weight parts,the procedure of Example 25 was otherwise repeated to mold the resincomposition into a sheet and evaluate its hardness, permanentcompression set, thermoplasticity, and melting viscosity by the methodsdescribed hereinbefore. The physical values are presented in Tables 4 to6.

EXAMPLE 28

Except that the formulating level of PP3 was changed to 100 weightparts, the procedure of Example 25 was otherwise repeated to mold theresin composition into a sheet and evaluate its hardness, permanentcompression set, thermoplasticity, and melting viscosity by the methodsdescribed hereinbefore. The physical values are presented in Tables 4 to6.

COMPARATIVE EXAMPLE 11

ARPIB, crosslinking agent 3, and hydrosilylation catalyst were evenlyadmixed in the ratio indicated in Table 7 at room temperature and themixture was poured in a metal mold and allowed to stand at 150° C. for24 hours to let the crosslinking reaction go to completion. The physicalproperties of the resulting molding were evaluated. The physical valuesare presented in Table 7.

TABLE 6 Ex. 18 19 20 21 22 23 24 25 26 27 28 Component (A) ARPIB (Weight100 100 100 100 100 100 100 100 100 100 100 parts) Component (B) PP2(Weight parts) 25 25 25 25 35 35 50 — — — — Component (B) PP3 (Weightparts) — — — — — — — 25 25 50 100 Component (C) PW-90 (Weight 50 100 150200 100 250 200 100 150 100 100 parts) Crosslinking agent 3 (Weight 9 99 9 9 9 9 9 9 9 9 parts) Hydrosilylation catalyst (ul) 50 50 50 50 50 5050 50 50 50 50 Parmanent compression set (%) 22 21 22 29 43 26 33 25 2844 52 Hardness (JIS A: immediately after 72 60 37 28 67 42 51 52 26 7789 press) Thermoplasticity ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯

TABLE 7 Compar. Ex. 10 11 Component (A) ARPIB (Weight — 100  parts)Crosslinking agent 3 (Weight —  9 parts) Hydrosilylation catalyst (ul) —50 Parmanent compression set (%) 21  7 Hardness (JIS A: immediatelyafter 56 20 press) Thermoplasticity ◯ X

The thermoplastic elastomer composition of the invention, specificallyExamples 18, 19, 20 and 21, varied widely in hardness over the range of28–72 (JTS A), and, yet, showed permanent compression set values of theorder of 20%, thus having good compression set characteristics andthermoplasticity while retaining the characteristics of an isobutylenepolymer. It is also apparent that compared with Santoplain 211-45 shownin Comparative Example 10, the composition of the invention is lower inhardness and excellent in the vibration damping property with a highvalue of tan δ which is a marker of vibration damping property.

INDUSTRIAL APPLICABILITY

The thermoplastic elastomer composition of the invention hasthermoplasticity with good rubber-like characteristics and is excellentnot only in moldability but also in both permanent compression set andvibration damping properties so that it can be used in a variety ofapplications such as sealing materials, vibration damping materials, andvibration preventing materials.

1. A thermoplastic elastomer composition comprising an unsaturated bond-containing isobutylene polymer (A), an olefinic resin (B), and a hydrosilyl group-containing compound as a cross-linking agent, wherein the unsaturated bond-containing isobutylene polymer (A) contains an average of 1 to 10 unsaturated bond per molecule and the crosslinking of the unsaturated bond-containing isobutylene polymer (A) is effected by the dynamic crosslinking at melt-kneading of the unsaturated bond-containing isobutylene polymer (A) with the olefinic resin (B).
 2. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated bond-containing isobutylene polymer (A) is a block copolymer comprising a polymer block (a) composed predominantly of isobutylene and a polymer block (b) composed predominantly of an aromatic vinyl compound.
 3. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated bond-containing isobutylene polymer (A) is an alkenyl group-terminated polymer.
 4. The thermoplastic elastomer composition according to claim 1, wherein the olefinic resin (B) content is 10 to 200 weight parts relative to 100 weight parts of the unsaturated bond-containing isobutylene polymer (A).
 5. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated bond-containing isobutylene polymer (A) is a polymer produced by synthesizing an isobutylene polymer not containing an unsaturated bond in the first place and then introducing an unsaturated bond thereinto.
 6. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated bond-containing isobutylene polymer (A) is an allyl-terminated polymer produced by causing allyltrimethylsilane to act on a polymer not containing an unsaturated bond at the molecular chain terminus but terminating in a chlorine atom.
 7. The thermoplastic elastomer composition according to claim 2, wherein the unsaturated bond-containing isobutylene polymer (A) contains said unsaturated bond within the molecular chain of the polymer block (b) composed predominantly of an armatic vinyl compound.
 8. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated bond-containing isobutylene polymer (A) has an intermolecularly crosslinked structure.
 9. The thermoplastic elastomer composition according to claim 1, comprising a plasticizer (C).
 10. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated bond-containing isobutylene polymer (A) is a polymer having a number average molecular weight of 1,000 to 500,000.
 11. The thermoplastic elastomer composition according to claim 1, wherein the unsaturated bond-containing isobutylene polymer (A) contains a monomer unit derived from isobutylene in a proportion of not less than 50 weight % based on the total weight of the polymer (A).
 12. The thermoplastic elastomer composition according to claim 1, wherein the olefinic resin (B) is polyethylene or polypropylene.
 13. The thermoplastic elastomer composition according to claim 9, wherein the plasticizer (C) is a paraffinic oil. 